The present invention embodies and is an improvement upon the abrading tool disclosed in U.S. Pat. No. 3,365,772 to Robert C. Collins. While the tool of that patent is very well adapted for its intended purposes, certain difficulties have been encountered in using it to remove thick barnacles or other marine growths from exposed surfaces of seawalls, piers, pilings and similar structures. Barnacle growth often exceeds three inches in thickness, and sometimes the rotatably mounted abrading discs in the tool shown in the aforementioned patent tend to ride across the barnacle surfaces instead of biting into and removing them from the underlying structure. The same difficulty can be encountered when using the tool to remove solidified concrete spills from road surfaces or undesired concrete droppings in building structures.